Baseline Hematologic Reserve and Laboratory-Defined Leukopenia/Neutropenia During Vancomycin Therapy: A Real-World Risk-Stratification Cohort Study

BACKGROUND: Laboratory-defined leukopenia/neutropenia may occur during vancomycin therapy, but mild threshold-crossing abnormalities do not necessarily establish definite drug-induced toxicity. OBJECTIVE: To develop and evaluate a risk-stratification strategy based on baseline hematologic reserve and vancomycin treatment duration. METHODS: /L during therapy or within 3 days after discontinuation. A 4-component baseline hematologic reserve score was constructed from WBC, ANC, monocyte count, and hemoglobin. RESULTS: < .001). The highest risk was observed in high-risk patients treated for >14 days, with an event rate of 75.0%. The baseline score model showed moderate performance (area under the curve [AUC] 0.697), whereas the extended model incorporating the score-defined risk group, treatment duration, and clinical covariates improved discrimination (AUC 0.786). CONCLUSION AND RELEVANCE: A 4-component baseline hematologic reserve score combined with treatment duration may help identify patients who warrant closer complete blood count monitoring during vancomycin therapy. These findings should be interpreted as laboratory-event risk stratification rather than proof of definite vancomycin-induced toxicity or as a mandatory discontinuation threshold.